Such social media sites as Facebook and Twitter are enormously useful for reporting, distributing and aggregating information about earthquakes. But don't overlook the apps you can download to your cellphone or to such tablets as the iPad. Scott Paulson and I took at look at the offerings and decided that you can't go wrong with apps like USGS Seismic and Tectonic. There's also a good app called iTsunami, covering a related area of seismicity.